[dv] riscv_pmp_out_of_bounds_test fails with sim mismatch

[imphil]

• Seed: 2031
• ibex revision: 93a76b390081b6b3b6cea2671c469f9293b998f2
• test: riscv_pmp_out_of_bounds_test (one iteration)

2021-06-03T07:41:56.6319853Z riscv_pmp_out_of_bounds_test.22
2021-06-03T07:41:56.6320251Z -------------------------------
2021-06-03T07:41:56.6320757Z Test binary: out/seed-2031/instr_gen/asm_test/riscv_pmp_out_of_bounds_test_22.o
2021-06-03T07:41:56.6321529Z sim log: out/seed-2031/rtl_sim/riscv_pmp_out_of_bounds_test.22/sim.log
2021-06-03T07:41:56.6322150Z ibex : out/seed-2031/rtl_sim/riscv_pmp_out_of_bounds_test.22/trace_core_00000000.csv
2021-06-03T07:41:56.6322723Z spike : out/seed-2031/instr_gen/spike_sim/riscv_pmp_out_of_bounds_test.22.csv
2021-06-03T07:41:56.6323065Z Mismatch[1]:
2021-06-03T07:41:56.6323387Z ibex[13133] : pc[8000e0a4] srai	x7,x30,0x2: t2:fffffefe 
2021-06-03T07:41:56.6324054Z spike[13133] : pc[ffffffff80001780] addi    a3, a3, -124: a3:80032dc4 
2021-06-03T07:41:56.6324472Z Mismatch[2]:
2021-06-03T07:41:56.6324947Z ibex[13134] : pc[8000e0b2] lw	x22,1484(x2): s6:00010048 
2021-06-03T07:41:56.6325402Z spike[13134] : pc[ffffffff800017f0] csrr    t4, mepc: t4:8000e08c 
2021-06-03T07:41:56.6325749Z Mismatch[3]:
2021-06-03T07:41:56.6326068Z ibex[13135] : pc[8000e0b6] or	x23,x23,x7: s7:fffffeff 
2021-06-03T07:41:56.6326453Z spike[13135] : pc[ffffffff800017f4] csrr    t4, mcause: t4:00000007 
2021-06-03T07:41:56.6326791Z Mismatch[4]:
2021-06-03T07:41:56.6327330Z ibex[13136] : pc[8000e0ba] lbu	x1,-926(x2): ra:000000ff 
2021-06-03T07:41:56.6327758Z spike[13136] : pc[ffffffff800017f8] c.li    a6, 3: a6:00000003 
2021-06-03T07:41:56.6328170Z Mismatch[5]:
2021-06-03T07:41:56.6328489Z ibex[13137] : pc[8000e0be] c.xor	x9,x14: s1:01000424 
2021-06-03T07:41:56.6328878Z spike[13137] : pc[ffffffff80001802] c.li    a6, 8: a6:00000008 
2021-06-03T07:41:56.6329227Z 271651 instructions left in trace spike
2021-06-03T07:41:56.6329526Z [FAILED]: 12041 matched, 288774 mismatch

https://dev.azure.com/lowrisc/lowrisc-private/_build/results?buildId=42835&view=results

[tomeroberts]

This looks to be the same root cause as #1165 (random addresses are chosen for load/store access sequences and some of those addresses hit memory regions that cause access exceptions in the ISS)